Use custom route tables to manage network communication - Cloud Enterprise Network

Enterprise Edition transit routers support custom route tables. After you create a custom route table for a transit router, you can associate the custom route table with network instances to establish network communication. The transit router forwards network traffic from network instances by querying the custom route table. You can add custom routes to custom route tables and associate custom route tables with prefix lists to control traffic forwarding.

Background information

Each Enterprise Edition transit router has a default system route table. Enterprise Edition transit routers also support custom route tables. Each Basic Edition transit router has a default system route table. Basic Edition transit routers do not support custom route tables. For more information about transit router editions, see View the edition of a transit router.

The system route table of a transit router is isolated from the custom route tables. The following content describes the system route table and custom route tables:

System route tables are automatically created by the system. When you create an Enterprise Edition transit router, the system automatically creates a system route table.
You can manually create custom route tables. Custom route tables are similar to virtual routing and forwarding (VRF) used by traditional routers. A custom route table is isolated from the system route table and other custom route tables.
After you connect a network instance to a transit router, you can configure associated forwarding to associate the network instance connection with a custom route table. The transit router forwards network traffic from the network instance by querying the custom route table. You can add custom routes to the custom route table and associate the custom route table with a prefix list to manage network communication.

Create a custom route table

Log on to the CEN console.
On the Instances page, click the ID of the CEN instance that you want to manage.
Go to the Basic Information > Transit Router tab and click the ID of the transit router that you want to manage.
On the details page of the transit router, click the Route Table tab.

In the left-side section, click Create Route Table. In the Create Route Table dialog box, set the following parameters and click OK.

Parameter	Description
Transit Router	Select the transit router for which you want to create a route table. The ID of the selected transit router is automatically displayed.
Route Table Name	Enter a name for the route table.
Description	Enter a description for the route table.
Tag	Add tags to the route table. Tag Key: The tag key can be up to 64 characters in length. It cannot be an empty string or start with `acs:` or `aliyun` or contain `http://` or `https://`. Tag Value: The tag value can be an empty string with a maximum length of 128 characters. It cannot start with `acs:` or `aliyun` or contain `http://` or `https://`. You can add one or more tags to a custom route table. For more information about tags, see Manage tags.
Multi-region ECMP Routing	Enable multi-region ECMP routing based on your business requirements. Multi-region ECMP routing is disabled by default. An Enterprise Edition transit router may learn routes from multiple virtual border routers (VBRs). If the routes have the same attributes other than region IDs, network traffic is forwarded based on the region IDs in alphabetical order. If multi-region ECMP routing is enabled for VBRs and the routes have the same attributes other than region IDs, the routes are considered equal-cost routes. For more information, see Multi-region ECMP routing for VBRs in different regions. To enable multi-region ECMP routing, turn on Multi-region ECMP Routing, read the information in the message that appears, and then click OK.

View the route tables of an Enterprise Edition transit router

Log on to the CEN console.
On the Instances page, click the ID of the CEN instance that you want to manage.
Go to the Basic Information > Transit Router tab and click the ID of the transit router that you want to manage.
On the details page of the transit router, click the Route Table tab.
In the left-side section, click the route table ID.
On the route table details page, you can view the following information:
- Routes of the transit router. For more information, see View routes of an Enterprise Edition transit router.
- Associated forwarding correlations. For more information, see Associated forwarding.
- Route learning correlations. For more information, see Route learning.
- Routing policies. For more information, see Routing policy overview.
- Routes generated based on a prefix list. For more information, see Prefix lists.
- Aggregate routes. For more information, see Aggregate routes.

View the route tables of a Basic Edition transit router

Log on to the CEN console.
On the Instances page, click the ID of the CEN instance that you want to manage.
Go to the Basic Information > Transit Router tab and click the ID of the transit router that you want to manage.
On the details page of the transit router, click the Route Table tab to view the following information:
- Routes of the transit router. For more information, see View routes of a Basic Edition transit router.
- Routing policies. For more information, see Routing policy overview.

Delete a custom route table

You can delete custom route tables that you no longer use. The system route table of a transit router cannot be deleted. Before you delete a custom route table, make sure that the following requirements are met:

The route table is not associated with an associated forwarding correlation. For more information, see Delete an associated forwarding correlation.
The route table is not associated with a route learning policy. For more information, see Delete a route learning policy.
The route table does not contain a custom route. For more information, see Delete a custom route from a route table of an Enterprise Edition transit router.
The route table is not associated with a prefix list. For more information, see Disassociate a prefix list from a transit router route table.
The route table does not contain an aggregate route. For more information, see Delete an aggregated route.

Log on to the CEN console.
On the Instances page, click the ID of the CEN instance that you want to manage.
Go to the Basic Information > Transit Router tab and click the ID of the transit router that you want to manage.
On the details page of the transit router, click the Route Table tab.
In the left-side section, click the route table ID.
In the Route Table Details section, click Delete.
In the Delete Route Table message, click OK.

References

CreateTransitRouterRouteTable: creates a custom route table for an Enterprise Edition transit router.
UpdateTransitRouterRouteTable: Modifies the name and description of an Enterprise Edition transit router route table.
ListTransitRouterRouteTables: queries the route tables of an Enterprise Edition transit router.
DeleteTransitRouterRouteTable: deletes a custom route table from an Enterprise Edition transit router.